Re: [Xen-devel] [PATCH v5] x86/setup: properly update PTEs if src/dst overlaps when relocating Xen image

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.04.18 at 12:26, <daniel.kiper@xxxxxxxxxx> wrote:
> @@ -1019,6 +1020,12 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>              bootsym(trampoline_xen_phys_start) = e;
>  
>              /*
> +             * All PTEs with PFNs above pte_update_limit
> +             * were updated earlier. Skip them.
> +             */
> +            pte_update_limit = PFN_DOWN(e + XEN_IMG_OFFSET);

I don't understand the comment: No PTE updates happen before this point
afaict. It is just that PTEs pointing above that address are not candidates
for relocation. I think the comment should at least mention the overlap
scenario your trying to deal with, with the important point being that there
may actually be PTEs pointing into [e, e + XEN_IMG_OFFSET).

The actual code adjustments look fine to me now, albeit I wonder whether
>= wouldn't be more appropriate to use.

Jan



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel